Many thanks for all your info. I wonder if there are any photos around? I must explain my interest - I was Supplies and Transport Manager for Shell products distribution in Nigeria throughout the Civil War (today job title would be Director of Logistics!). We supplied bitumen in drums from our plant at Lagos to Cotonou from where it was flown in by the DC6s to Uli ihiala for the extension of the road into a runway with dispersal points etc. At Easter 1968 my wife and I were in Cotonou watching and helping loading the standard lift of CSM and Heineken when we were offered a lift in for the fun of it - to my eternal regret I refused as I knew I'd be sacked on the spot if Shell ever heard about it).
Weapons were flown in from Sao Tome except for the French Navy Neptune from Cotonou with French arms (they flew in the radar shadow of a DC6 to avoid the Feds).
The Cotonou DC6s were maintained by Field Aircraft Services with a polyglot air crews. From memory they were rated at 20,000lbs cargo and normally lifted 24,000lbs. Watching takeoffs was heart stopping - at dusk very long run then out over the sea barely climbing (anyway they kept low to cross the Nigerian coastline below radar if possibl). upt ot three flights per night (on bonuses!)
I was also responsible for fuel supplies to the ICRC aid road convoys (and to the Fed Army and Air Force - SA mercenary pilots mostly), so immediately at the end of the war I drove into Biafra and saw Uli Ihiala (and the other military only airstrip) to suss out fuel aid routes (getting road tankers etc).
I was moved by the little cemetery of some 20 crew at the end of the runway - shortly afterwards the Fed Army bulldozed it away. Driving onto the 'runway' you went through the fuselage of a DC4? that had crashed and the two halves simply pulled apart. There were burnt out Connies etc on the dispersal points. But I had no camera, so no photos.
By the way, the C97s were never used. They were flown into Lagos by the US Government at the end of the war with the idea of replacing the aid flights, as 700,000 people were dying of starvation. But the Feds refused permission. They needed 115/145 which wqe didn't have in Nigeria but there was some in Cotonou so i organised a 'reverse lift' of road tankers to truck it into Lagos (that took some organising in 24 hours I can tell you - talk about bureaucracy!).
So I had tremendous admiration for those crews - it was 'Fate is the Hunter' type story.